INTRODUCTION. Ixxxv 
Order 3. 
PODACTINARIA. 
Polypi having the gastric cavity surrounded by four vertical membranaceous sep/a, at 
the upper end of which are placed four pairs of intestiniform reproductive organs. The 
tentacula discoidal, pedunculated, not tubular as in Zoantharia and Alcyonaria, but 
organized much in the same way as in Bchinoderma. The mouth proboscidiform, and 
the fauces surrounded by numerous internal, filiform, contractile appendices. 
The genus LucurNnaria is the only known representative of this zoological type, and 
comprises no coralligenous polypi. 
Sub-class 2. 
HYDRARIA. 
Polypes sertulariens, Audouin and Milne Edwards, Recherches sur les Anim. sans Verteb., faites aux iles 
Chausay, in Ann. des Sc. Nat., Ist series, vol. xv, p. 18, 1828, ap. Lamarck, Hist. des An. sans Verteb. 
2d ed., vol. ii., p. 105; Sertulariacea (in parte), Blainville, Manuel d’Actinologie, p. 465, 1834 ; 
Zoocorallia oligactinia, Ehrenberg, Coral. Roth. Meeres, p. 67, 1834; Zoophyta Hydroida, Johnston, in 
Mag. of Zool. and Bot., vol. i, p. 447, 1837; Polyparia, Gray, Synop. Brit. Mus. ; Nudibranchiata, Farre, 
on the Structure of Polypi, Phil. Trans. 1837; Hydrozoa, R. Owen, Lectures on the Comp. Anat. of the 
Inverteb. Animals, p. 82, 1843; Hydroidea, Dana, Exploring Expedition, Zooph. p. 685, 1846 ; 
Anthozoa Hydroidea, Johnston, British Zooph, 2d ed. p. 5, 1847. 
Polypi with a simple, non-lamelliferous, digestive cavity. No internal generative 
organs. ‘Tentacula filiform and subverrucose. 
The naked, fresh-water zoophytes of the genus Hypra constitute the type of this 
group, and till very lately were considered as being closely allied to Sertularia, Campanu- 
laria, &c.; but the recent observations of divers zoologists tend to establish that all the 
coralligenous animals of this form belong to the class of Medusa. Till this question is 
decided, it would therefore be idle to make any modifications in the systematic arrange- 
ment of these problematic polypi, and it will suffice for us to refer the reader to Dr. 
Johnston’s valuable work on ‘British Zoophytes,’ for the characters of the generic 
divisions generally adopted. 
